Add flashing screen

app/src/main/java/com/topjohnwu/magisk/utils/AdaptiveList.java

@@ -0,0 +1,36 @@
+package com.topjohnwu.magisk.utils;
+
+import android.support.v7.widget.RecyclerView;
+
+import java.util.ArrayList;
+
+public class AdaptiveList<E> extends ArrayList<E> {
+
+    private Runnable callback;
+    private RecyclerView mView;
+
+    public AdaptiveList(RecyclerView v) {
+        mView = v;
+    }
+
+    public void updateView() {
+        mView.getAdapter().notifyDataSetChanged();
+        mView.scrollToPosition(mView.getAdapter().getItemCount() - 1);
+    }
+
+    public void setCallback(Runnable cb) {
+        callback = cb;
+    }
+
+    public boolean add(E e) {
+        boolean ret = super.add(e);
+        if (ret) {
+            if (callback == null) {
+                updateView();
+            } else {
+                callback.run();
+            }
+        }
+        return ret;
+    }
+}

app/src/main/java/com/topjohnwu/magisk/utils/Utils.java

@@ -44,19 +44,19 @@ public class Utils {
     private static final int APK_UPDATE_NOTIFICATION_ID = 2;
 
     public static boolean itemExist(Shell shell, String path) {
-        String command = "if [ -e " + path + " ]; then echo true; else echo false; fi";
+        String command = "[ -e " + path + " ] && echo true || echo false";
         List<String> ret = shell.su(command);
         return isValidShellResponse(ret) && Boolean.parseBoolean(ret.get(0));
     }
 
     public static void createFile(Shell shell, String path) {
         String folder = path.substring(0, path.lastIndexOf('/'));
-        String command = "mkdir -p " + folder + " 2>/dev/null; touch " + path + " 2>/dev/null; if [ -f \"" + path + "\" ]; then echo true; else echo false; fi";
+        String command = "mkdir -p " + folder + " 2>/dev/null; touch " + path + " 2>/dev/null;";
         shell.su_raw(command);
     }
 
     public static void removeItem(Shell shell, String path) {
-        String command = "rm -rf " + path + " 2>/dev/null; if [ -e " + path + " ]; then echo false; else echo true; fi";
+        String command = "rm -rf " + path + " 2>/dev/null";
         shell.su_raw(command);
     }